A possible mutation of a fluorescence polymorphism.

The segregation of the Q-band polymorphisms in 32 families have been studied. From 90 matings in these families, there were a total of 208 offspring. In one of these offspring it could be shown that there had been a change of a fluorescent polymorphism, resulting in the loss of fluorescent intensity in the satellite of a chromosome 21. The origin of such a 'mutation' and a consideration of mutation rates is discussed.